Problem: Expand and combine like terms. $(2-7m^6)^2=$
Explanation: We can expand this expression using the "perfect square" pattern (where $P$ and $Q$ can be any monomial): $(P+Q)^2=P^2+2PQ+Q^2$ Since we have a minus sign, let's rewrite the binomial as a sum where the second term is negative, then use the pattern. $\begin{aligned} &\phantom{=}\left(2-7m^6\right)^2 \\\\ &=\left(2+\left(-7m^6\right)\right)^2 \\\\ &=(2)^2+2(2)(-7m^6)+(-7m^6)^2 \\\\ &=4-28m^6+49m^{12} \\\\ &=49m^{12}-28m^6+4 \end{aligned}$